The present invention relates, in general, to a single turn ferrite rod antenna and method. More particularly, the present invention relates to an antenna and method resulting in a high "Q", high sensitivity antenna suitable for use in conjunction with miniaturized receivers.
Requirements for decreased size of paging and radio receiver packages have necessitated simplification and down-sizing of antenna elements to meet manufacturing and size constraints. However, the antenna must, nevertheless, provide a sufficiently high "Q" (low loss) while simultaneously exhibiting sufficient radiated signal sensitivity. Existing technologies have been unsatisfactory in meeting these constraints.
U.S. Pat. No. 3,267,478 issued to Schiefer on Aug. 16, 1966 for a tunable ferromagnetic rod loop antenna describes an antenna comprising a cylindrical core surrounded by a sleeve of electrically conductive material. A gap is shown running the entire length of the sleeve and has a plurality of capacitors, equidistantly spaced, distributed throughout its length. A coupling winding surrounds at least a portion of the core and includes a pair of wires for coupling the antenna assembly to the receiver. Normally symmetrical conductors or coaxial conductors are used to establish electrical connection to the receiver input stage. The antenna shown provides no means for ready mounting to a printed circuit board. As a consequence, such an antenna would not be suitable for use with today's more compact mounting and advantageous circuit interconnection techniques.
In like manner, U.S. Pat. No. 3,594,805 issued to Chardin on July 20, 1971 for a ferrite rod antenna with a longitudinally split sleeve, describes an antenna in which the resonant frequency may be adjusted by varying the inductance of a first split sleeve. The opposite edges of the longitudinal split are connected by a plurality cf capacitors uniformly distributed over the length of the sleeve. The first sleeve additionally includes a longitudinal slot approximately one-third of the length of the rod. A second split sleeve is positioned over the first sleeve to adjust the inductance of the assembly by masking portions of the longitudinal slot. No adequate means are disclosed for mounting the antenna to a printed circuit board, rather the same prior art provision for wire leads forming the electrical connections between the circuit and the antenna are described.
Additional antenna construction techniques include that disclosed in U.S. Pat. No. 3,946,397 issued to Irwin on Mar. 23, 1976 for antenna arrangement having an inductor combined with integral series resonating circuits. The antenna disclosed includes a spiral inductor or coil which is divided into a number of segments interconnected by individual capacitive elements to form a number of series-resonant circuits. While an effective antenna technique, it would be highly desirable to provide an antenna exhibiting a high "Q" and high sensitivity which is simpler to implement and may be more readily connected to a printed circuit board.
It would therefore be highly desirable to provide an expedient structure for and method of mounting and electrically connecting an antenna to a printed circuit board which does not require the use of wire leads and in which any tuning adjustment would be located remotely from the antenna structure itself.